L-methionine (L-MET), an essential sulfur-containing amino acid belonging to the aspartate family, plays a critical role in agricultural crops by influencing their nutritional value. In this study, the objective was to evaluate the efficacy of exogenously administered L-MET in enhancing maize growth, yield, and essential metabolic processes. Two different concentrations of L-MET, namely 50 and 100 mg L-1, were compared to an untreated control to assess their impact on two maize hybrids, Dk-6317 and Dk-9108. The results demonstrated a significant positive effect on various parameters, including plant height, leaf characteristics, photosynthetic rate, chlorophyll content, and yield. The exogenous application of L-MET led to notable improvements in carotenoid levels, total soluble phenolics, proline, glycine betaine, malondialdehyde, hydrogen peroxide, and ion homeostasis in both maize hybrids, with statistical significance (P ≤ 0.05) observed. Furthermore, a correlation analysis was conducted to examine the relationship between the investigated traits. The results indicated a progressive correlation between hundred grain weights (HGW) and the number of leaves (NL), cob length, and photosynthetic pigments. This suggests that photosynthesis traits significantly contribute to yield. Consequently, the findings strongly indicate that foliar application of L-MET has the potential to stimulate maize growth and enhance traits that contribute to increased yield by modulating various physiological and biochemical processes.